前两天更新了网络的 Basic、Intermediate，可以看前面的文章。
【润学】计算机网络八股文英文版(1)
【润学】计算机网络八股文英文版(2)
今天更新 Advanced。点击此处可获取音频。
Advanced Interview Questions
21. What is the TCP protocol?
TCP or TCP/IP is the Transmission Control Protocol/Internet Protocol. It is a set of rules that decides how a computer connects to the Internet and how to transmit the data over the network. It creates a virtual network when more than one computer is connected to the network and uses the three ways handshake model to establish the connection which makes it more reliable.
21. 什么是TCP协议？
TCP 或 TCP/IP 是传输控制协议/Internet 协议。它是一组规则，用于决定计算机如何连接到 Internet 以及如何通过网络传输数据。它在多台计算机连接到网络时创建一个虚拟网络，并使用三种方式握手模型建立连接，使其更加可靠。
22. What is the UDP protocol?
UDP is the User Datagram Protocol and is based on Datagrams. Mainly, it is used for multicasting and broadcasting. Its functionality is almost the same as TCP/IP Protocol except for the three ways of handshaking and error checking. It uses a simple transmission without any hand-shaking which makes it less reliable.
22. 什么是 UDP 协议？
UDP 是用户数据报协议，基于数据报。主要用于组播和广播。除了握手和错误检查三种方式外，它的功能几乎与 TCP/IP 协议相同。它使用简单的传输，没有任何握手，这使得它不太可靠。
23. Compare between TCP and UDP
- TCP is Connection-Oriented Protocol, while UDP is Connectionless Protocol.
- TCP is More Reliable, while UDP is Less Reliable.
- TCP transmission is slower than UDP transmission.
- TCP’s Packets order can be preserved or can be rearranged, while UDP’s Packets order is not fixed and packets are independent of each other.
- TCP Uses three ways handshake model for connection, while UDP uses No handshake for establishing the connection.
- TCP packets are heavy-weight, while UDP packets are light-weight.
- TCP Offers error checking mechanism, while UDP offers No error checking mechanism.
- Protocols like HTTP, FTP, Telnet, SMTP, HTTPS, etc use TCP at the transport layer, while Protocols like DNS, RIP, SNMP, RTP, BOOTP, TFTP, NIP, etc use UDP at the transport layer.
23. TCP 和 UDP 的比较
| TCP/IP | UDP |
|---|---|
| 面向连接的协议 | 无连接协议 |
| 更可靠 | 不太可靠 |
| 传输速度较慢 | 更快的传输 |
| 数据包顺序可以保留或重新排列 | 数据包顺序不固定，数据包相互独立 |
| 使用三种方式握手模型进行连接 | 无需握手即可建立连接 |
| TCP 数据包是重量级的 | UDP数据包是轻量级的 |
| 提供错误检查机制 | 没有错误检查机制 |
| HTTP、FTP、Telnet、SMTP、HTTPS 等协议在传输层使用 TCP | DNS、RIP、SNMP、RTP、BOOTP、TFTP、NIP 等协议在传输层使用 UDP |
24. What is the ICMP protocol?
ICMP is the Internet Control Message Protocol. It is a network layer protocol used for error handling. It is mainly used by network devices like routers for diagnosing the network connection issues and crucial for error reporting and testing if the data is reaching the preferred destination in time. It uses port 7 by default.
24. 什么是 ICMP 协议？
ICMP 是 Internet 控制消息协议。它是用于错误处理的网络层协议。它主要被路由器等网络设备用于诊断网络连接问题，并且对于错误报告和测试数据是否及时到达首选目的地至关重要。它默认使用端口 7。
25. What do you mean by the DHCP Protocol?
DHCP is the Dynamic Host Configuration Protocol.
It is an application layer protocol used to auto-configure devices on IP networks enabling them to use the TCP and UDP-based protocols. The DHCP servers auto-assign the IPs and other network configurations to the devices individually which enables them to communicate over the IP network. It helps to get the subnet mask, IP address and helps to resolve the DNS. It uses port 67 by default.
25. DHCP 协议是什么意思？
DHCP 是动态主机配置协议。
它是一种应用层协议，用于自动配置 IP 网络上的设备，使它们能够使用基于 TCP 和 UDP 的协议。DHCP 服务器会自动将 IP 和其他网络配置单独分配给设备，从而使它们能够通过 IP 网络进行通信。它有助于获取子网掩码、IP 地址并有助于解析 DNS。它默认使用端口 67。
26. What is the ARP protocol?
ARP is Address Resolution Protocol. It is a network-level protocol used to convert the logical address i.e. IP address to the device’s physical address i.e. MAC address. It can also be used to get the MAC address of devices when they are trying to communicate over the local network.
26.什么是ARP协议？
ARP是地址解析协议。它是一种网络级协议，用于将逻辑地址（即 IP 地址）转换为设备的物理地址（即 MAC 地址）。当设备尝试通过本地网络进行通信时，它还可用于获取设备的 MAC 地址。
27. What is the FTP protocol?
FTP is a File Transfer Protocol. It is an application layer protocol used to transfer files and data reliably and efficiently between hosts. It can also be used to download files from remote servers to your computer. It uses port 27 by default.
27. 什么是FTP协议？
FTP 是一种文件传输协议。它是一种应用层协议，用于在主机之间可靠有效地传输文件和数据。它还可用于将文件从远程服务器下载到您的计算机。它默认使用端口 27。
28. What is the MAC address and how is it related to NIC?
MAC address is the Media Access Control address. It is a 48-bit or 64-bit unique identifier of devices in the network. It is also called the physical address embedded with Network Interface Card (NIC) used at the Data Link Layer. NIC is a hardware component in the networking device using which a device can connect to the network.
28. 什么是MAC地址，它与网卡有什么关系？
MAC 地址是媒体访问控制地址。它是网络中设备的 48 位或 64 位唯一标识符。它也称为嵌入在数据链路层的网络接口卡 (NIC) 的物理地址。NIC 是网络设备中的硬件组件，设备可以使用它连接到网络。
29. Differentiate the MAC address with the IP address
The difference between MAC address and IP address are as follows:
- MAC address is Media Access Control Address, while IP address is Internet Protocol Address.
- MAC address has 6 or 8-byte hexadecimal number, while IP address is 4 (IPv4) or 16 (IPv6) Byte address.
- MAC address is embedded with NIC, while IP address is obtained from the network.
- MAC address is Physical Address, while IP address is Logical Address.
- MAC address Operates at Data Link Layer, while IP address Operates at Network Layer…
- MAC address Helps to identify the device, while IP address Helps to identify the device connectivity on the network.
29. 区分MAC地址和IP地址
MAC地址和IP地址的区别如下：
| MAC地址 | IP地址 |
|---|---|
| 媒体访问控制地址 | 互联网协议地址 |
| 6 或 8 字节的十六进制数 | 4 (IPv4) 或 16 (IPv6) 字节地址 |
| 它嵌入了网卡 | 是从网络上获取的 |
| 实际地址 | 逻辑地址 |
| 在数据链路层运行 | 在网络层运行。 |
| 帮助识别设备 | 帮助识别网络上的设备连接。 |
30. What is a subnet?
A subnet is a network inside a network achieved by the process called subnetting which helps divide a network into subnets. It is used for getting a higher routing efficiency and enhances the security of the network. It reduces the time to extract the host address from the routing table.
30. 什么是子网？
子网是通过称为子网划分的过程实现的网络内部的网络，该过程有助于将网络划分为子网。用于获得更高的路由效率，增强网络的安全性。它减少了从路由表中提取主机地址的时间。
31. Compare the hub vs switch
- The Hub Operates at Physical Layer, while the switch Operates at Data Link Layer.
- The Hub adopts Half-Duplex transmission mode, while the switch adopts Full-Duplex transmission mode.
- Ethernet devices can be connected by Hub, while LAN devices can be connected by switch.
- The Hub is Less complex, less intelligent, and cheaper, while the switch is Intelligent and effective.
- No software support for the administration in Hub, while Administration software support is present in switch.
- The Hub has Less speed up to 100 MBPS, while the switch Supports high speed in GBPS.
- The Hub is Less efficient as there is no way to avoid collisions when more than one nodes sends the packets at the same time, while the switch is More efficient as the collisions can be avoided or reduced as compared to Hub.
31. 比较集线器与交换机
| 集线器 | 交换机 |
|---|---|
| 在物理层运行 | 在数据链路层运行 |
| 半双工传输方式 | 全双工传输模式 |
| 可连接以太网设备 | 可以连接局域网设备 |
| 更简单、更智能、更便宜 | 智能高效 |
| 管理没有软件支持 | 存在管理软件支持 |
| 速度较慢，最高可达 100 MBPS | 支持 GBPS 高速 |
| 效率较低，因为当多个节点同时发送数据包时无法避免冲突 | 与 Hub 相比，可以避免或减少碰撞，因此效率更高 |
32. What is the difference between the ipconfig and the ifconfig?
Both the ipconfig and the ifconfig are Used to get the TCP/IP summary and allows to changes the DHCP and DNS settings. The difference between ipconfig and ifconfig are as follows:
- The ipconfig is Internet Protocol Configuration, while the ifconfig is Interface Configuration.
- The ipconfig is Command used in Microsoft operating systems to view and configure network interfaces, while the ifconfig is Command used in MAC, Linux, UNIX operating systems to view and configure network interfaces.
- Both the ipconfig and the ifconfig are Used to get the TCP/IP summary and allows to changes the DHCP and DNS settings.
32. ipconfig 和 ifconfig 有什么区别？
都是用于获取 TCP/IP 摘要并允许更改 DHCP 和 DNS 设置，区别如下：
| ipconfig | ifconfig |
|---|---|
| 互联网协议配置 | 接口配置 |
| Windows 操作系统中用于查看和配置网络接口的命令 | MAC、Linux、UNIX 操作系统中用于查看和配置网络接口的命令 |
33. What is the firewall?
The firewall is a network security system that is used to monitor the incoming and outgoing traffic and blocks the same based on the firewall security policies. It acts as a wall between the internet (public network) and the networking devices (a private network). It is either a hardware device, software program, or a combination of both. It adds a layer of security to the network.
33. 什么是防火墙？
防火墙是一种网络安全系统，用于监控传入和传出流量，并根据防火墙安全策略阻止流量。它充当互联网（公共网络）和网络设备（专用网络）之间的墙。它可以是硬件设备、软件程序或两者的组合。它为网络增加了一层安全性。
34. What are Unicasting, Anycasting, Multicasting and Broadcasting?
- Unicasting: If the message is sent to a single node from the source then it is known as unicasting. This is commonly used in networks to establish a new connection.
- Anycasting: If the message is sent to any of the nodes from the source then it is known as anycasting. It is mainly used to get the content from any of the servers in the Content Delivery System.
- Multicasting: If the message is sent to a subset of nodes from the source then it is known as multicasting. Used to send the same data to multiple receivers.
- Broadcasting: If the message is sent to all the nodes in a network from a source then it is known as broadcasting. DHCP and ARP in the local network use broadcasting.
34. 什么是单播、任播、组播和广播？
- **单播：**如果消息从源发送到单个节点，则称为单播。这通常在网络中用于建立新连接。
- **任播：**如果消息从源发送到任何节点，则称为任播。它主要用于从内容交付系统中的任何服务器获取内容。
- **多播：**如果消息从源发送到节点的子集，则称为多播。用于向多个接收者发送相同的数据。
- **广播：**如果消息从源发送到网络中的所有节点，则称为广播。本地网络中的 DHCP 和 ARP 使用广播。
35. What happens when you enter google.com in the web browser?
Below are the steps that are being followed:
- Check the browser cache first if the content is fresh and present in cache display the same.
- If not, the browser checks if the IP of the URL is present in the cache (browser and OS) if not then request the OS to do a DNS lookup using UDP to get the corresponding IP address of the URL from the DNS server to establish a new TCP connection.
- A new TCP connection is set between the browser and the server using three-way handshaking.
- An HTTP request is sent to the server using the TCP connection.
- The web servers running on the Servers handle the incoming HTTP request and send the HTTP response.
- The browser process the HTTP response sent by the server and may close the TCP connection or reuse the same for future requests.
- If the response data is cacheable then browsers cache the same.
- Browser decodes the response and renders the content.
35. 当您在网络浏览器中输入 google.com 时会发生什么？
以下是正在遵循的步骤：
- 首先检查浏览器缓存，如果内容是新的并且存在于缓存中，那么直接显示。
- 如果没有，浏览器检查 URL 的 IP 是否存在于缓存（浏览器和操作系统）中，如果没有，则请求操作系统使用 UDP 进行 DNS 查找，以从 DNS 服务器获取 URL 的相应 IP 地址以建立一个新的 TCP 连接。
- 使用三次握手在浏览器和服务器之间设置新的 TCP 连接。
- 使用 TCP 连接将 HTTP 请求发送到服务器。
- 服务器上运行的 Web 服务器处理传入的 HTTP 请求并发送 HTTP 响应。
- 浏览器处理服务器发送的 HTTP 响应，并可能关闭 TCP 连接或在未来的请求中重用。
- 如果响应数据是可缓存的，那么浏览器会缓存相同的数据。
- 浏览器解码响应并呈现内容。
欢迎关注公众号获取音频。
【润学】计算机网络八股文英文版(3)
